/** 
* *********  操作实例  ************** 
*   var map = new HashMap(); 
*   map.put("key1","Value1"); 
*   map.put("key2","Value2"); 
*   map.put("key3","Value3"); 
*   map.put("key4","Value4"); 
*   map.put("key5","Value5"); 
*   alert("size："+map.size()+" key1："+map.get("key1")); 
*   map.remove("key1"); 
*   map.put("key3","newValue"); 
*   var values = map.values(); 
*   for(var i in values){ 
*       document.write(i+"："+values[i]+"   "); 
*   } 
*   document.write("<br>"); 
*   var keySet = map.keySet(); 
*   for(var i in keySet){ 
*       document.write(i+"："+keySet[i]+"  "); 
*   } 
*   alert(map.isEmpty()); 
*/  
  
function HashMap(){  
  //定义长度  
  var length = 0;  
  //创建一个对象  
  var obj = new Object();  

  /** 
  * 判断Map是否为空 
  */  
  this.isEmpty = function(){  
      return length == 0;  
  };  

  /** 
  * 判断对象中是否包含给定Key 
  */  
  this.containsKey=function(key){  
      return (key in obj);  
  };  

  /** 
  * 判断对象中是否包含给定的Value 
  */  
  this.containsValue=function(value){  
      for(var key in obj){  
          if(obj[key] == value){  
              return true;  
          }  
      }  
      return false;  
  };  

  /** 
  *向map中添加数据 
  */  
  this.put=function(key,value){  
      if(!this.containsKey(key)){  
          length++;  
      }  
      obj[key] = value;  
  };  

  /** 
  * 根据给定的Key获得Value 
  */  
  this.get=function(key){  
      return this.containsKey(key)?obj[key]:null;  
  };  

  /** 
  * 根据给定的Key删除一个值 
  */  
  this.remove=function(key){  
      if(this.containsKey(key)&&(delete obj[key])){  
          length--;  
      }  
  };  

  /** 
  * 获得Map中的所有Value 
  */  
  this.values=function(){  
      var _values= new Array();  
      for(var key in obj){  
          _values.push(obj[key]);  
      }  
      return _values;  
  };  

  /** 
  * 获得Map中的所有Key 
  */  
  this.keySet=function(){  
      var _keys = new Array();  
      for(var key in obj){  
          _keys.push(key);  
      }  
      return _keys;  
  };  

  /** 
  * 获得Map的长度 
  */  
  this.size = function(){  
      return length;  
  };  

  /** 
  * 清空Map 
  */  
  this.clear = function(){  
      length = 0;  
      obj = new Object();  
  };  
}
module.exports = HashMap;